In which type of study does the researcher have no control over the variables being studied?

A cross-sectional study involves observing a particular point in time to analyze the relationships between variables without manipulating them. Researchers collect data from participants at a single point or over a short period, assessing various factors that may relate to the outcome of interest, but they do not intervene or control the variables being studied. This type of study often provides a snapshot of the characteristics of a population or a phenomenon, enabling researchers to identify potential associations but not causal relationships.

In contrast, experimental studies involve active manipulation of one or more independent variables to see how they affect a dependent variable, giving researchers control over the factors they are studying. Prospective studies track participants over time to see how certain variables influence outcomes, still allowing some control over how data is collected. Retrospective studies look back at existing data or records to find correlations or patterns, but researchers typically define the study parameters based on the existing variables. Hence, the absence of control in a cross-sectional study distinguishes it from these other types of research.